Our invention relates to a circuit for programming the search circuit of a radio receiver, and particularly to such a circuit for programming a large number of channels with a relatively small number of switches.
Search receivers are used extensively to monitor a plurality of radio channels. A typical search receiver includes a circuit that causes the desired channels to be sequentially scanned. If, when scanned, a channel has a signal present, scanning stops until the signal ends. After the signal ends, scanning resumes until another signal is present on a channel when scanned. As far as we are aware, previous search receivers used or required a separate switch for each channel. Each channel switch was selectively positioned for scanning or skipping. However, if the receiver was capable of receiving a large number of channels, sixteen not being unusual, or if the receiver was of the small personal type, the available panel space for the necessary switches limited the number of channels which could be programmed. Further, the large number of switches made a small receiver unattractive or difficult to handle.
Accordingly, a primary object of our invention is to provide a new and improved circuit for programming the search circuit of a radio receiver.
Another object of our invention is to provide a new and improved programming circuit for a search receiver that saves power in its readout circuit.
Another object of our invention is to provide a new and improved circuit that permits a relatively large number of radio channels to be programmed for scanning or for skipping with only three manual switches needed on the receiver panel.
Another object of our invention is to provide a new and improved circuit that permits a relatively large number of radio channels to be programmed for scanning or for skipping but that prevents accidental or undesired programming of a channel.
Where a radio receiver can scan a large number of channels, the user may forget which channels were previously programmed for scanning and which channels were previously programmed for skipping.
Accordingly, another object of our invention is to provide a new and improved circuit that permits a relatively large number of radio channels to be programmed for scanning or for skipping, and that provides a visual indication of which channels were previously programmed to be scanned and which channels were previously programmed to be skipped.